Counterfeiting and forgeries continue to proliferate. A hot area of counterfeiting is consumer products, such as cellular phones and cameras. Often cellular phones include interchangeable faceplates. (Or a camera includes a logo plate, which is easily replicated by thieves.). A common counterfeiting scenario involves counterfeiting the faceplate, and then passing off the counterfeit faceplate as genuine.
One solution is to provide steganographic auxiliary data in the faceplate to help prevent or detect counterfeiting. The data can be decoded to determine whether the object is authentic. The auxiliary data may also provide a link to a network resource, such as a web site or data repository. The absence of expected auxiliary data may also provide a clue regarding counterfeiting.
One form of encoding is accomplished with digital watermarking. Digital watermarking systems typically have two primary components: an encoder that embeds the watermark in a host media signal, and a decoder (or reader) that detects and reads the embedded watermark from a signal suspected of containing a watermark. The encoder embeds a watermark by altering the host media signal. The decoding component analyzes a suspect signal to detect whether a watermark is present. In applications where the watermark encodes information, the decoder extracts this information from the detected watermark.
One challenge to the developers of watermark embedding and reading systems is to ensure that the watermark is detectable even if the watermarked media content is transformed in some fashion. The watermark may be corrupted intentionally, so as to bypass its copy protection or anti-counterfeiting functions, or unintentionally through various transformations (e.g., scaling, rotation, translation, etc.) that result from routine manipulation of the content. In the case of watermarked images, such manipulation of the image may distort the watermark pattern embedded in the image.
A watermark can have multiple components, each having different attributes. To name a few, these attributes include function, signal intensity, transform domain of watermark definition (e.g., temporal, spatial, frequency, etc.), location or orientation in host signal, redundancy, level of security (e.g., encrypted or scrambled), etc. The components of the watermark may perform the same or different functions. For example, one component may carry a message, while another component may serve to identify the location or orientation of the watermark. Moreover, different messages may be encoded in different temporal or spatial portions of the host signal, such as different locations in an image or different time frames of audio or video. In some cases, the components are provided through separate watermarks.
There are a variety of alternative embodiments of an embedder and detector. One embodiment of the embedder performs error correction coding of a binary message, and then combines the binary message with a carrier signal to create a component of a watermark signal. It then combines the watermark signal with a host signal. To facilitate detection, it may also add a detection component to form a composite watermark signal having a message and detection component. The message component includes known or signature bits to facilitate detection, and thus, serves a dual function of identifying the mark and conveying a message. The detection component is designed to identify the orientation of the watermark in the combined signal, but may carry an information signal as well. For example, the signal values at selected locations in the detection component can be altered to encode a message.
One embodiment of the detector estimates an initial orientation of a watermark signal in a host signal, and refines the initial orientation to compute a refined orientation. As part of the process of refining the orientation, this detector computes at least one orientation parameter that increases correlation between the watermark signal and the host signal when the watermark or host signal is adjusted with the refined orientation.
Another detector embodiment computes orientation parameter candidates of a watermark signal in different portions of the target signal, and compares the similarity of orientation parameter candidates from the different portions. Based on this comparison, it determines which candidates are more likely to correspond to a valid watermark signal.
Yet another detector embodiment estimates orientation of the watermark in a target signal suspected of having a watermark. The detector then uses the orientation to extract a measure of the watermark in the target. It uses the measure of the watermark to assess merits of the estimated orientation. In one implementation, the measure of the watermark is the extent to which message bits read from the target signal match with expected bits. Another measure is the extent to which values of the target signal are consistent with the watermark signal. The measure of the watermark signal provides information about the merits of a given orientation that can be used to find a better estimate of the orientation. Of course other watermark embedder and detectors can be suitably interchanged with some embedding/detecting aspects of the present invention.
Some techniques for embedding and detecting watermarks in media signals are detailed in the assignee's U.S. patent application Ser. No. 09/503,881 (now U.S. Pat. No. 6,614,914), U.S. Pat. No. 6,122,403 and PCT Patent Application PCT/US02/20832 (published in English as WO 03/005291) mentioned above.
Injection molding is known as an efficient means for producing articles of manufacture. GE Corporation has recently developed an injection molding process, which can provide a logo or graphic in an object manufactured through injection molding (i.e., see GE's so-called “In-Mold Decoration” process). In a typical in-mold decorating process, a printed substrate is formed into a three-dimensional shape and placed into a mold. Molten resin is then injected into a mold cavity space behind the formed substrate, forming a single molded part. Further details to these techniques can be found, e.g., in U.S. Pat. Nos. 6,465,102, 6,458,913 and 6,117,384, which are each herein incorporated by reference.
One improvement provides steganographic auxiliary data to facilitate authentication of an injection-molded part. In one implementation, auxiliary data is provided on a first print receiving material, e.g., through printing or laser engraving. In some cases, auxiliary data is steganographically encoded in an image, graphic or design. The encoded image, graphic or design is printed or engraved on the first print receiving material. The printed, first print receiving material is then combined with a second material through an injection molding process. The first print receiving material provides a protective layer for the steganographic auxiliary data. The auxiliary data provides an authentication tool to help determine whether the object is authentic.
Another aspect of the present invention is an injection-molded object including a hidden steganographic signal encoded (or embedded) therein.
Yet another aspect of the present invention is an authentication process to determine whether an object is authentic. The authentication process detects an auxiliary signal hidden in the object. The signal is decoded to determine whether the object is authentic.
The foregoing and other features and advantages of the present invention will be even more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.